Ten to 17% of children between the ages of 4 and 16 yrs. meet the criteria for recurrent abdominal pain (RAP) a condition that accounts for at least 5% of all pediatric office visits and often leads to significant disability (e.g., school absence). From 30%-66% of children with RAP will go on to experience similar pain as adults leading to the suggestion that RAP and irritable bowel syndrome (IBS) may be the same syndrome at different developmental stages. Similar to IB S, 20-68% of children reporting abdominal pain also experience alterations it/bowel patterns (constipation and/or diarrhea). Although the cause(s) of RAP (as well as IBS) are unknown, factors contributing to the symptom experience and health care seeking are likely to include both physiological and psychosocial. Recently, evidence suggests that stress and an increased GI immune response induce GI inflammation, which contributes to GI symptom experience. In our current study we are comparing three groups of children: those with RAP who are referred to tertiary medical attention (RAP-GI); who have RAP but do not seek tertiary care (i.e., beyond their pediatrician) (RAP-Ped); and those who do not have RAP symptoms (Controls) in order to describe and compare among these children (ages 7-10): 1) GI symptoms (abdominal pain and bowel patterns) and functional disability (pain interfering with activity, school absences) using retrospective and prospective symptom measures; 2) autonomic nervous system function (spectral and non-spectral analysis of heart rate variability and urine catecholamines); 3) child and parent pain coping skills, parent modeling and reinforcement of illness behavior; and 4) psychological distress (anxiety, depression, and somatization). The Specific Aims of this proposed Supplement are to among the three groups: 1) Describe and compare evidence of GI inflammation using the urinary sucrose/lactulose/mannitol/sucralose sugar permeability test (PT) and the fecal calprotectin concentration, and 2) Examine the relationship between GI inflammation and symptom experience (abdominal pain frequency and intensity) and change in stool pattern. This proposed interdisciplinary study would be the first in children to examine concurrently both physiologic and psychosocial factors related to RAP, and its functional consequences, and to compare these to a sample of children with RAP who do not seek tertiary medical attention. Understanding the potential role of GI inflammation in RAP could assist in developing strategies to treat this ubiquitous and little understood condition in order to obviate its attendant financial and emotional cost. [unreadable] [unreadable] [unreadable]